Theoretical Study on the Electronic States of Layered Fluorinated Carbon Materials

层状氟化碳材料电子态的理论研究

基本信息

批准号：
13640324
负责人：
KUSAKABE Koichi
金额：
$ 2.18万
依托单位：
NIIGATA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

项目摘要

We theoretically investigated fluorinated graphite and fluorinated boron-nitrides using the first-principles molecular-dynamics method and clarified that the fluorination of layered graphite and related materials can be utilized as 1) a synthesis method of a wide-gap semiconductor whose band gap is controllable by changing composition and 2) a synthesis method of a nanometer-scale magnet. Major results of our project are summarized as follows.1. Fluorinated graphite C_nF is a layered material whose structure is regarded as a stacking of ultra-thin diamond films with fluorinated surfaces. The material has a direct gap when n=l,2,3, while the gap becomes indirect if n exceeds 4. We proposed that the material may be utilized for fabrication of optical devices including semiconductor LASER and determined wavelengths of expected output theoretically. We proposed that the material is synthesized as a natural superlattice and estimated energy levels of electrons and holes in this 2-dimensional electronic system. Stability and characteristics of (BN)_nF are theoretically predicted.2. We proposed a way to obtain magnetic nanographite from nanometer-scale graphite and finite nanotubes. Existence of magnetism in nanographite, which has been expected by several authors, is shown theoretically. Moreover, it is controllable by chemical treatments including hydrogenation, fluorination and oxygen-substitution of zigzag-edged nanographite in nanometer scale. This is a theoretical prediction of synthesis methods of magnetic materials without magnetic elements.3. New developments in the first-principles electronic-structure calculations including correlation effects were achieved. We proposed an extension of the Kohn-Sham equation. Acceleration of the trans-correlated method is realized.

我们理论上使用第一原则分子动力学方法研究了氟化石墨和氟化的硼硝酸盐，并澄清了分层石墨和相关材料的氟化，可用于1）1）一种宽隙半导体的合成方法，其宽隙半导体可控制频带隙是可控的。通过更改组成和2）纳米尺度磁铁的合成方法。我们项目的主要结果总结如下1。氟化石墨C_NF是一种分层材料，其结构被视为具有氟化表面的超薄钻石膜的堆叠。当n = l，2,3时，该材料具有直接的间隙，而如果n超过4，则差距会间接。我们提议该材料可用于制造光学设备，包括半导体激光器和确定的预期输出的波长。我们提出，该材料在此二维电子系统中合成为天然超晶格和电子和孔的估计能级。理论上预测（BN）_nf的稳定性和特征2。我们提出了一种从纳米尺度石墨和有限纳米管获取磁性纳米仪的方法。从理论上讲，纳米仪中磁性的存在已被几位作者所期望。此外，它可以通过化学处理，包括在纳米尺度上的曲折边缘纳米仪在内的氢化，氟化和氧化。这是没有磁元素的磁性材料合成方法的理论预测3。第一原理电子结构计算（包括相关效应）的新发展。我们提出了Kohn-Sham方程的扩展。实现了反相关方法的加速度。